1. Field of the Invention
The present invention relates to a method and apparatus for producing embroidery data used by a sewing machine.
2. Related Art Statement
It has conventionally been practiced to produce a batch of embroidery data for forming stitches filling an embroidery area, such that the embroidery data consist of a multiplicity of sets of stitch data, each set of stitch data being coordinate data representative of a stitch position where a sewing needle penetrates a work cloth. Therefore, the production of embroidery data needs operator's enormous labor to specify or input the coordinates of all the stitch positions, and in addition the embroidery data thus produced is bulky for memory means. In this background, it has been proposed to approximate an original pattern by a polygon, divide or reduce the polygon to simple polygonal blocks such as rectangles and triangles, and utilize, as embroidery data, sets of coordinate data indicative of the vertices of the polygonal blocks thus obtained. In the case where an original embroidery area at least partially outlined by a curve is embroidered, it has been practiced to approximate the curved outline or partial area by an "arcuate" block as shown in FIG. 19.
However, the conventionally used polygonal or arcuate blocks cannot sufficiently represent or approximate a curved portion of an original pattern. In order to increase the degree of representation or approximation of polygonal or arcuate blocks, it is required to divide the curved portion into more increased number of smaller blocks. This means that an increased amount of coordinate data is required for producing an embroidery with excellent external appearance. Thus, the problem that embroidery data is bulky has not been solved yet.